Linkage Design in Two‐Dimensional Covalent Organic Frameworks for High Iodine Uptake

Abstract

Radioactive iodine waste in the nuclear field is harmful to the environment and human health. Covalent organic frameworks (COFs) are a novel kind of porous organic material with a well‐fine and unformal structure, which is an excellent candidate as a solid adsorbent for iodine adsorption. Herein, a linkage design is proposed for effective iodine adsorption. Imine‐linkage COF (I‐COF) and hydrazone‐linked COF (H‐COF) are constructed under solvothermal conditions. The Brunauer–Emmett–Teller surface area of H‐COF is as high as 1747 m2 g−1. Furthermore, the H‐COF shows high porosity, stability, and rich atoms in the linkage. As a result, the work outperforms most of the previous reports in iodine capture with a high capture value at 5.72 g g−1.

2D Mesoporous Naphthalene‐Based Conductive Heteroarchitectures toward Long‐Life, High‐Capacity Zinc‐Iodine Batteries

“…Significantly, compared with pure iodine (619.8 and 631.2 eV), [ 19 ] the shift of the peak position to the lower binding energy represents a strong interaction between iodine and the polymer. [ 20 ] The one pair of iodine coupling peaks at 618.4/629.9 eV is assigned to triiodide ion (I 3 − ), attributed to their electron transfer. [ 1,21 ] The above can be further proved by the 0.4 eV shift of peak fraction of the N1s core level after iodine loading compared with the synthetic sample (Figure 3c).…”

Construction of a conjugated covalent organic framework for iodine capture

“…Due to their high surface area, low density and regular pore structure, COFs are suitable as a solid-phase adsorbent and have been studied as adsorbent materials for iodine capture. [10][11][12][13][14][15][16][17][18][19][20][21] For example, Fang et al synthesized tetrathiafulvalene-based COFs and achieved excellent iodine adsorption capacity through the synergistic effect of physical and chemical adsorption. 16 Recently we have also reported a pyrene-based two-dimensional COF (TFPPy-TMPD-COF) with a vapor capacity of 4.8 g g −1 due to the combination of chemisorption and physisorption, 19 in which the introduction of 2,3,5,6-tetramethyl-p-phenylenediamine (TMPD) was helpful for changing the pore environment to enhance the iodine adsorption capacity of the COF.…”

Green mechanochemical synthesis of imine-linked covalent organic frameworks for high iodine capture

“…7 Compared to other benchmark porous materials such as zeolites, amorphous POPs, and MOFs, COFs have unparalleled structural advantages including ultralow density, regular networks, high porosity, exceptional structural modularity, and superb synthetic versatility, which underpin their broad applications in gas storage, catalysis, energy storage, water harvesting, environmental remediation, etc. [8][9][10][11] Since the first report of using COFs as iodine adsorbents in 2017, 12 enormous scientific efforts have been devoted to the fabrication of high-performance COF adsorbents through three main routes: (1) de novo synthesis of COF adsorbents containing iodine affinity sites such as imine, [13][14][15] hydrazone, 16 cationic species, 17 amino, 18 hydrazides, 19 thiophene, 20 tetrathiafulvalene, 21 phosphine; 22 (2) grafting ionic groups onto already-synthesized COFs by post-synthetic modification; 23 and (3) constructing hierarchically porous COFs through supercritical CO 2 drying, 24 freezedrying, 25 and template-assisted modulated synthesis. 26 Despite substantial advances, the synthesis of COF adsorbents still heavily relies on conventional solvothermal synthesis, which entails multiday synthesis, the usage of toxic organic solvents, high temperatures, and anaerobic conditions.…”